The invention relates to a seat frame of a vehicle seat with a seat carrier having at least one side part, with a front arm means and with a longitudinal adjustment device, the side part being provided with a first bore and a bearing member, more specifically a bolt or a shaft, projecting from the front arm means and passing through said first bore so that an upper pivot joint is realized between the side part and the front arm means with the front arm means being connected to the longitudinal adjustment device by way of a lower pivot joint.
Seat frames of this type have come to be widely used, U.S. Pat. No. 6,264,274 B1 being cited herein as a mere example of the state of the art. Usually, the side part of the seat carrier is hinge-linked, in the rear region thereof, to the pair of rails of the longitudinal adjustment device by way of a rear swiveling support. A four-bar linkage is thus obtained which is composed of the side part, the front parallelogram arm, the seat rail of the pair of rails and the rear swiveling support. An adjustment member is allocated to this four-bar linkage, said adjustment member being situated in most cases at the hinge point between the rear swiveling support and the side part. By releasing it, the seat carrier may be adjusted in height relative to the longitudinal adjustment device.
Many users not only ask for height adjustment but also for inclination adjustment of the seat carrier relative to the longitudinal adjustment device. Such adjustment devices are conventional in the art. The height of the front edge of the seat carrier is adjusted, the rear region of the seat carrier substantially remains at the same height.
It is well known to provide the front parallelogram arm with a variable length for the purpose of achieving such an adjustment of the inclination. Seat frames are known in which the front parallelogram arm is realized by a pair of arms consisting of an upper and of a lower arm that are pivotally joined together in one common joint. By varying the angle formed by said two arms, the height of the front edge of the seat may be adjusted. A device for adjusting the angular position of the upper arm relative to the seat carrier is provided for this purpose.
Whereas the seat frame of the type mentioned herein above has four links, i.e., is a so-called four-link arrangement, the seat frame provided with a possibility of adjusting the height of the front edge of the seat is a five-link arrangement. The latter seat frame is more complex than the seat frame of the type mentioned herein above since it requires more parts, for example, an adjustment device with hand or motor drive.
In manufacturing seat frames for vehicle seats, is an aim to produce seats with height adjustment only and to include additional inclination adjustment in a simple manner in an effort to permit low-cost manufacturing of the two configuration alternatives for the seat frame. This is where the invention comes to bear. It is the object of the invention to improve a seat frame of the type mentioned herein above in such a manner that, for both alternatives, i.e., a seat frame of adjustable height but not of adjustable inclination an the one hand and a seat frame of adjustable height and inclination on the other hand, as many like parts as possible may be used, that, for both alternatives, the kinematics in the region of adjustment of the height adjustment may be almost identical and the production simple.
In view of the seat frame of the type mentioned herein above, the solution to this object is to provide the side part with an additional, second bore, to provide, alternatively, either a parallelogram arm or a pair of arm means comprising an upper arm, a lower arm, and a device for adjusting the angular position. Both arms are pivotally joined together in one common joint. The upper arm has a pivot member which is spaced from the common joint and by means of which it can be carried in the second bore. The device for adjusting the angular position adjusts the angular position of the upper arm relative to the seat carrier. The axis of the common joint is substantially aligned with the first bore in a certain position of adjustment of said device. The lower arm has bearing means and is hingeable to the longitudinal adjustment device and is provided, between the two hinge points thereof, with substantially the same length the parallelogram arm shows with between the hinge point of its bolt, i.e., the upper pivot joint, and the lower pivot joint.
In accordance with the invention, the same seat carrier may be used for the two alternative embodiments of the seat frame. Thanks to their two bores, the seat carriers are designed in such a manner that they may be connected either with one parallelogram arm, or with the upper arm of a pair of arm means.
The kinematics of the height adjustment device is very similar in the two alternatives. If the device for adjusting the inclination of the seat frame of adjustable inclination is set in such a manner that the axis of the common joint is aligned with the first bore, the kinematics of the height adjustment of the thus set seat of adjustable inclination is the same as the kinematics of the height adjustment of the other alternative, i.e., of the seat frame the inclination of which cannot be adjusted. The length of the upper double arm between the two hinge points thereof substantially squares with the distance between the two bores of the side part.
Generally speaking, the invention makes it possible to provide a seat frame of simple construction that is manufactured in two alternatives, the one with and the other one without inclination adjustment. All of the other parts of the vehicle seat can remain unchanged. It is only necessary to provide enough space for handling the adjustment device when it is driven manually, which may be in the form of an opening for the axle of such an adjustment device. If the adjustment device is electrical, space is provided for the drive anyway.
In a development of the invention, the seat carrier is provided, in a manner well known in the art, with a left and a right side part, a left and a right front parallelogram arm and two pairs of rails of the longitudinal adjustment in the first alternative. In the (second) alternative, with adjustable inclination, two pairs of arm means are substituted for the two front parallelogram arms. It is thereby possible, but not necessary, to provide an adjustment device on either side of the seat.
The two front parallelogram arms, or, in the case of the alternative embodiment, the two pairs of arm means, are preferably joined together by means of a tie bar. As a result thereof, the whole seat frame is stiffer end a lateral displacement or inclination is prevented. It is made certain that the two front parallelogram arms, or the pairs of arm means, are always substantially paralleled.
In a preferred development, the second bore is nearer a front edge of the seat than the first bore. As a result thereof, the required adjustment device may be realized in relative proximity to the front edge of the seat, thus being conveniently within reach for manual drive. In principle, the second bore may also be provided at a greater distance from the front edge of the seat than the first bore.
In a preferred embodiment, the two bores are provided at the same distance from the associated pair of rails of the longitudinal adjustment device. Put another way, a connecting line of the two bores is oriented substantially parallel to a longitudinal dimension of the side part. Preferably, the two bores and one hinge axle of the rear swiveling support of the side part are substantially aligned.
In a development, the already mentioned, certain or determined position of adjustment of the adjustment device, in which the common joint is substantially aligned with the first bore, is situated in a region that extends from the central position of the adjustment device toward a lower setting of the front edge of the seat. This means that, in the first alternative of the seat frame without inclination adjustment, the front edge of the seat is actually too low for a standard passenger. In the alternative with inclination adjustment, the front edge of the seat can be raised by a greater distance than it can be lowered as compared to the first alternative.